CRM 2011 Online - Silverlight/WCF alwasy get an error - wcf

Question

I have a SL 5 project.In the SilverlightApplication.Web I have a Silverlight-enabled WCF service, which connects to a Sharepoint and do something. (returns a byte[]) I use this as a Service Reference in my SilverlightApplication. On my local computer it works well, but not in CRM Online.
My web.config looks like this:
<?xml version="1.0"?>
<configuration>
<configSections>
</configSections>
<system.web>
<compilation debug="true" targetFramework="4.0" />
</system.web>
<system.serviceModel>
<serviceHostingEnvironment aspNetCompatibilityEnabled="true" multipleSiteBindingsEnabled="true"/>
<behaviors>
<serviceBehaviors>
<behavior name="">
<serviceMetadata httpsGetEnabled="true" />
<serviceDebug includeExceptionDetailInFaults="true" />
</behavior>
<behavior name="">
<serviceMetadata httpGetEnabled="true" />
<serviceDebug includeExceptionDetailInFaults="true" />
</behavior>
<behavior name="DisableServiceCertificateValidation">
<serviceCredentials>
<clientCertificate>
<authentication certificateValidationMode="None" revocationMode="NoCheck"/>
</clientCertificate>
</serviceCredentials>
</behavior>
</serviceBehaviors>
</behaviors>
<bindings>
<customBinding>
<binding name="SilverlightApplication4.Web.AuthService.customBinding0" >
<binaryMessageEncoding maxReadPoolSize="2147483647" maxSessionSize="2147483647" maxWritePoolSize="2147483647" />
<httpsTransport maxBufferPoolSize="2147483647" maxBufferSize="2147483647" maxReceivedMessageSize="2147483647" transferMode="StreamedResponse" />
</binding>
</customBinding>
</bindings>
<services>
<service name="SilverlightApplication4.Web.AuthService">
<endpoint address="" binding="customBinding" bindingConfiguration="SilverlightApplication4.Web.AuthService.customBinding0"
contract="SilverlightApplication4.Web.AuthService" />
<endpoint address="mex" binding="mexHttpsBinding" contract="IMetadataExchange" />
</service>
</services>
<!--<behaviors>
<serviceBehaviors>
<behavior name="">
<serviceMetadata httpGetEnabled="true" />
<serviceDebug includeExceptionDetailInFaults="false" />
</behavior>
</serviceBehaviors>
</behaviors>-->
<!--<serviceHostingEnvironment aspNetCompatibilityEnabled="true" multipleSiteBindingsEnabled="true" />-->
</system.serviceModel>
</configuration>
And my clientconfig:
<configuration>
<system.serviceModel>
<bindings>
<customBinding>
<binding name="CustomBinding_AuthService">
<binaryMessageEncoding />
<httpsTransport maxReceivedMessageSize="2147483647" maxBufferSize="2147483647" transferMode="StreamedResponse"/>
</binding>
</customBinding>
</bindings>
<client>
<endpoint binding="customBinding"
bindingConfiguration="CustomBinding_AuthService" contract="AuthService.AuthService"
name="CustomBinding_AuthService" />
</client>
</system.serviceModel>
</configuration>
And the error text is: (from Fiddler)
HTTP Error 500 - Internal Server Error
<?xml version="1.0"?>
<error xmlns:xsd="http://www.w3.org/2001/XMLSchema" xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance">
<exception>Unhandled Exception: System.ServiceModel.FaultException`1[[Microsoft.Xrm.Sdk.OrganizationServiceFault, Microsoft.Xrm.Sdk, Version=5.0.0.0, Culture=neutral, PublicKeyToken=31bf3856ad364e35]]: System.InvalidOperationException: Microsoft Dynamics CRM has experienced an error. Reference number for administrators or support: #EE5999FBDetail:
<OrganizationServiceFault xmlns:i="http://www.w3.org/2001/XMLSchema-instance" xmlns="http://schemas.microsoft.com/xrm/2011/Contracts">
<ErrorCode>-2147220970</ErrorCode>
<ErrorDetails xmlns:d2p1="http://schemas.datacontract.org/2004/07/System.Collections.Generic" />
<Message>System.InvalidOperationException: Microsoft Dynamics CRM has experienced an error. Reference number for administrators or support: #EE5999FB</Message>
<Timestamp>2013-05-29T06:40:56.383069Z</Timestamp>
<InnerFault i:nil="true" />
<TraceText i:nil="true" />
</OrganizationServiceFault>
</exception>
<parameters xsi:nil="true" />
<displaytitle />
<displaytextencoded />
<displaytext />
<description>CRM Parameter Filter - Invalid parameter 'V
s
aVD
??urn:AuthService/TestD??w?/?%?C?m/????D,D*?
D??Vhttps://nngkft.crm4.dynamics.com/%7B635053590270003339%7D/WebResources/AuthService.svc
V#Test


' in Request.InputStream on page /Handlers/WebResource.ashx
The raw request was 'POST /{635053590270003339}/WebResources/AuthService.svc' called from https://nngkft.crm4.dynamics.com/%7B635053590270003339%7D/WebResources/new_spsl.</description>
<file>Not available</file>
<line>Not available</line>
<details>Not available</details>
<traceInfo />
<requesturl>http://nngkft.crm4.dynamics.com:82/Handlers/WebResource.ashx?name=AuthService.svc</requesturl>
<pathAndQuery>/Handlers/WebResource.ashx?name=AuthService.svc</pathAndQuery>
<source>ASHX_XML</source>
<stacktrace />
</error>
Does anybody have a good idea?
Thanks and regards,
Peter